There is a conventional technique of recognizing figures such as characters represented by a color image without being affected by the illumination condition or the like. In this technique, it is made possible to recognize a subject figure with high precision by using combinations of main color components of the subject figure in order to cope with separation caused in a figure area of a recognition subject by an influence of, for example, a shadow depending upon the illumination condition or a coated surface thinned by deterioration or the like condition.
FIG. 1 shows an example of a system for removing the influence of the illumination condition or the like in the conventional figure reading. The conventional figure reading system includes image input means, main color extraction means, combination generation means, figure area extraction means and figure recognition means.
The conventional system having such a configuration operates as described hereafter. With respect to a color image input from the image input unit, the main color extraction means extracts main colors on the basis of a local peak value in a color histogram included in the color image, and resolves the color image into main color images respectively of the extracted main colors. The combination generation means combines the main color images generated by the resolving and generates combined images. The figure area extraction means extracts character area candidates from the main color images and the combined images. The figure recognition means conducts character recognition processing on all extracted character area candidates, and obtains the best character reading result on the basis of character recognition frequencies in a result of the character recognition processing.
Furthermore, there is a pattern recognition apparatus for selecting a main color having a distance from a main color which is a certain threshold or less from among the main colors in the RGB color space in the pattern recognition of characters or the like indicated in a color image (see, for example, Patent Document 1).
Patent Document 1: JP 2003-16444A